Add links to CCG from S2S guides (#1010)

Following up on #1008 by adding a few cross-links from existing guides.

Very much open to feedback on the copy itself or its positioning within
the S2S guides.

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Mandy Hubbard <[email protected]>

docs/faq/faq.md

@@ -139,7 +139,7 @@ _en-grok_
 The first prototype for ngrok was committed on [March 20th,
 2013](https://github.com/inconshreveable/ngrok/commit/8f4795ecac7f92c6b5a8c8970c65f26e5315fe4e).
 
-## Why does port scanning my ngrok domain show other open ports {#open-ports-on-domain}
+## Why does port scanning my ngrok domain show other open ports? {#open-ports-on-domain}
 
 ngrok uses a shared set of servers to service both HTTP(s)/TLS and TCP traffic.
 All HTTP(s)/TLS traffic is serviced on ports 80 and 443. For TCP traffic each
@@ -153,5 +153,15 @@ traffic to be routed to the correct customer. For TCP traffic ngrok uses the
 IP and port to indicate which customer to route traffic to.
 
 As with all publicly accessible IPs and ports on the internet anyone can send
-traffic to those endpoints, but ngrok provides a [number of mechanisms](https://ngrok.com/docs/guides/security-dev-productivity/) to control
+traffic to those endpoints, but ngrok provides a [number of
+mechanisms](/docs/guides/other-guides/security-dev-productivity/) to control
 what traffic actually gets routed to you ngrok agent or sdk.
+
+## Why is my vendor asking me to install ngrok for 'site-to-site connectivity'? {#site-to-site-end-customer}
+
+Your vendor wants to create a secure persistent connection between your network
+and theirs, which allows them to access and take action on your services and
+data.
+
+For details about what ngrok is, how to install the ngrok agent, and how to work
+with your vendor to implement adequate security practices, see our [end customer installation guide](/docs/guides/site-to-site-connectivity/end-customers/).

docs/guides/site-to-site-connectivity/apis-mtls.mdx

@@ -18,6 +18,13 @@ to locally running APIs. The connection will be end-to-end encrypted using mutua
 For a deeper understanding for how mTLS is implemented within ngrok, reference the [Mutual TLS module
 page](/http/mutual-tls/).
 
+:::tip
+Ready to educate your customers with information about why they must install the
+ngrok agent to enable site-to-site connectivity, your shared options for
+architecture and security, and operational best practices? Send them to our [end
+customer installation guide](end-customers.mdx).
+:::
+
 ## **Prerequisites**
 
 A certificate authority (CA) is required for mTLS. The CA is responsible for issuing and digitally

docs/guides/site-to-site-connectivity/apis.mdx

@@ -16,6 +16,13 @@ However, we understand there are times when you may
 wish to configure an unencrypted connection such as during testing or proof of concept. Therefore, we provide the
 steps in this guide, but we recommend configuring mTLS before going to production.
 
+:::tip
+Ready to educate your customers with information about why they must install the
+ngrok agent to enable site-to-site connectivity, your shared options for
+architecture and security, and operational best practices? Send them to our [end
+customer installation guide](end-customers.mdx).
+:::
+
 ## Install the ngrok agent
 
 [Download](https://download.ngrok.com) the appropriate version and install it on the same subnet as the

docs/guides/site-to-site-connectivity/dbs-mtls.mdx

@@ -21,6 +21,13 @@ site.
 For a deeper understanding for how mTLS is implemented within ngrok, reference the [Mutual TLS module
 page](/http/mutual-tls/).
 
+:::tip
+Ready to educate your customers with information about why they must install the
+ngrok agent to enable site-to-site connectivity, your shared options for
+architecture and security, and operational best practices? Send them to our [end
+customer installation guide](end-customers.mdx).
+:::
+
 ## **Prerequisites**
 
 A certificate authority (CA) is required for mTLS. The CA is responsible for issuing and digitally

docs/guides/site-to-site-connectivity/dbs.mdx

@@ -16,6 +16,13 @@ However, we understand there are times when you may
 wish to configure an unencrypted connection such as during testing or proof of concept. Therefore, we provide the
 steps in this guide, but we recommend configuring mTLS before going to production.
 
+:::tip
+Ready to educate your customers with information about why they must install the
+ngrok agent to enable site-to-site connectivity, your shared options for
+architecture and security, and operational best practices? Send them to our [end
+customer installation guide](end-customers.mdx).
+:::
+
 ## Install the ngrok agent
 
 [Download](https://download.ngrok.com) the appropriate version and install it on the same subnet as the